Interference measurement method and apparatus for user equipment having multiple heterogeneous communication modules in wireless communication system

ABSTRACT

An interference measurement method and a user equipment supporting the method are provided. The method enables the user equipment having multiple heterogeneous communication modules for Long Term Evolution (LTE), WiFi, Bluetooth and Global Positioning System (GPS) to perform interference measurement so as to avoid coexistence interference. The user equipment may perform effective communication by identifying non-preferred frequency bands and avoiding coexistence interference caused by the heterogeneous communication modules.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of a U.S.provisional application filed on Jan. 18, 2011 in the U.S. Patent andTrademark Office and assigned Ser. No. 61/433,651, and under 35 U.S.C.§119(a) of a Korean patent application filed on Dec. 21, 2011 in theKorean Intellectual Property Office and assigned Serial No.10-2011-0139376, the entire disclosures of which are hereby incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wireless communication system. Moreparticularly, the present invention relates to an interferencemeasurement method that enables a user equipment having multipleheterogeneous communication modules to avoid coexistence interference.

2. Description of the Related Art

In recent years, smartphones having WiFi, Bluetooth and GlobalPositioning System (GPS) modules have been rapidly popularized. Withthis trend, various communication technologies (for example, Long TermEvolution (LTE)/Universal Mobile Telecommunication System (UMTS) forcellular network communication, WiFi for wireless local areacommunication, Bluetooth for short-range wireless communication, andGNSS/GPS for location-based services, etc.) may coexist in the same userequipment. When heterogeneous communication technologies aresimultaneously used in the same user equipment, a problem ofinterference therebetween may arise. This problem has been discussedunder the name of In-Device Coexistence (IDC) in 3GPP.

While LTE/UMTS communication operates in various frequency bands,Bluetooth or WiFi communication operates in the Industrial ScientificMedical (ISM) band of 2400-2483.5 MHz. In particular, Band 40 (2300-2400MHz) and Band 7 Uplink (2500-2570 MHz) among multiple LTE/UMTS frequencybands are adjacent to the ISM band for Bluetooth or WiFi communication.Hence, when LTE/UMTS communication and Bluetooth or WiFi communicationare simultaneously conducted, a transmit signal for one communicationtechnology may be received as a receive signal for another communicationtechnology, thereby causing serious interference.

FIG. 3 illustrates 3GPP frequency bands for mobile communication aroundthe ISM band. As indicated by FIG. 3, use of WiFi channel 1 while Band40 is used for a mobile communication cell may cause seriousinterference, and use of WiFi channel 13 or 14 while Band 7 is used fora mobile communication cell may cause serious interference.

Hence, it is necessary to identify such mutual interference throughprecise measurement in the event of interference.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a method and apparatus that enable a userequipment having multiple heterogeneous communication modules for LTE,WiFi, Bluetooth and GPS to perform interference measurement so as toavoid coexistence interference.

In order to solve the above problems, a user equipment identifies atleast one frequency that is likely to be affected by interference andnotifies such frequency to a base station, so that the base station canconfigure suitable measurement. The user equipment may also notifynon-preferred frequency bands to the base station so that the basestation may take actions to avoid interference.

In accordance with an exemplary embodiment of the present invention, ameasurement method for a user equipment in a wireless communicationsystem is provided. The measurement method includes identifying, upondetection of activation of an interfering communication technology thatpotentially causes interference to cellular communication of the userequipment, at least one frequency that is likely to be affected by thepotential interference, sending a measurement configuration requestmessage including the identified at least one frequency that is likelyto be affected by the potential interference to a base station, andperforming, upon reception of a measurement configuration message fromthe base station, measurement according to measurement configurationsincluded in the measurement configuration message.

In accordance with another exemplary embodiment of the presentinvention, a user equipment capable of interference measurement in awireless communication system is provided. The user equipment includes atransceiver unit sending and receiving a signal to and from a basestation, and a control unit controlling a process of identifying, upondetection of activation of an interfering communication technology thatpotentially causes interference to cellular communication of the userequipment, at least one frequency that is likely to be affected by thepotential interference caused by the interfering communicationtechnology, for sending a measurement configuration request messageincluding the identified list of at least one frequency that is likelyto be affected by the potential interference to the base station, andfor performing, upon reception of a measurement configuration messagefrom the base station, measurement according to measurementconfigurations specified in the received message.

In accordance with another exemplary embodiment of the presentinvention, a system for coordinating measurement of in-deviceinterference is provided. The system comprises a base station, and aterminal that communicates with the base station, wherein the basestation instructs the terminal to measure in-device interference if theterminal determines that an interfering communication technology isactivated as the terminal is communicating with the base station.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates an LTE system architecture according to an exemplaryembodiment of the present invention;

FIG. 2 illustrates a hierarchy of wireless protocols in an LTE systemaccording to an exemplary embodiment of the present invention;

FIG. 3 illustrates 3GPP frequency bands for mobile communication aroundthe ISM band according to an exemplary embodiment of the presentinvention;

FIG. 4 is a message sequence chart illustrating an interferencemeasurement method according to an exemplary embodiment of the presentinvention;

FIG. 5 is a flowchart of a procedure performed by a user equipment suchas, for example the user equipment provided in FIG. 4 according to anexemplary embodiment of the present invention;

FIG. 6 is a message sequence chart illustrating an interferencemeasurement method according to an exemplary embodiment of the presentinvention;

FIG. 7 is a flowchart of a procedure performed by a user equipment suchas, for example, the user equipment provided in FIG. 6 according to anexemplary embodiment of the present invention; and

FIG. 8 is a block diagram of a user equipment according to an exemplaryembodiment of the present invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

In the description, cellular communication (or mobile communication) isfocused on the Long Term Evolution (LTE) system. However, variousexemplary embodiments of the present invention are applicable to anytype of cellular communication. As an example, an “interferingcommunication technology” refers to WiFI, Bluetooth or GPS technology(e.g., a WiFI, a Bluetooth or a GPS module) other than LTE technology(e.g., a LTE module). An LTE terminal may be referred to as a UserEquipment (UE), and an LTE base station may be referred to as an evolvedNode B (eNB).

FIG. 1 illustrates an LTE system architecture according to an exemplaryembodiment of the present invention.

Referring to FIG. 1, an LTE radio access network is composed of eNBs105, 110, 115 and 120, a Mobility Management Entity (MME) 125 and aServing-Gateway (S-GW) 130. A User Equipment (UE) 135 may connect to anexternal network through at least one of the eNBs 105 to 120 and theS-GW 130.

The eNBs 105 to 120 correspond to Node Bs of the Universal MobileTelecommunication System (UMTS). The eNB is connected to the userequipment 135 through a wireless channel, and may perform complexfunctions in comparison to an existing Node B. With regard to a LongTerm Evolution (LTE) system, because all user traffic includingreal-time services such as Voice over IP (VoIP) services is served byshared channels, it is necessary to perform scheduling on the basis ofcollected status information regarding buffers, available transmitpowers, and channels of user equipments. Each of the eNBs 105 to 120performs such a scheduling function. In most cases, a single eNBcontrols multiple cells. To achieve a data rate of 100 Mbps, the LTEsystem utilizes orthogonal frequency division multiplexing (OFDM) in a20 MHz bandwidth as radio access technology. The LTE system employsadaptive modulation and coding (AMC) to determine the modulation schemeand channel coding rate according to channel states of user equipments.The S-GW 130 provides data bearers, and creates and removes a databearer under control of the MME 125. The MME 125 performs variouscontrol functions including mobility management for user equipments, andis connected to multiple eNBs.

FIG. 2 illustrates a hierarchy of wireless protocols in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 2, in the LTE system, a user equipment (UE) and an eNBeach include a wireless protocol stack composed of a Packet DataConvergence Protocol (PDCP) layer 205 or 240, a Radio Link Control (RLC)layer 210 or 235, a Medium Access Control (MAC) layer 215 or 230, and aphysical (PHY) layer 220 or 225. The PDCP layer 205 or 240 performscompression and decompression of IP headers. The RLC layer 210 or 235reconfigures PDCP Protocol Data Units (PDUs) to a suitable size toconduct, for example, Automatic Repeat-reQuest (ARQ) operations. The MAClayer 215 or 230 is connected to multiple RLC layer devices in a userequipment, and multiplexes RLC PDUs into MAC PDUs or demultiplexes MACPDUs into RLC PDUs. The physical layer 220 or 225 converts upper layerdata into OFDM symbols by means of channel coding and modulation andtransmits the OFDM symbols through a wireless channel, or converts OFDMsymbols received through a wireless channel into upper layer data bymeans of demodulation and channel decoding and forwards the data toupper layers.

FIG. 4 is a message sequence chart illustrating an interferencemeasurement method according to an exemplary embodiment of the presentinvention.

When an interfering communication technology causes interference in anoperating frequency band, the user equipment needs to report suchinterference to a corresponding eNB. For reporting this coexistenceinterference using a measurement option defined in the standard, the eNBneeds to notify the user equipment of a suitable measurementconfiguration.

In LTE, an A3 measurement event is commonly used for measurementtriggering. An A3 event triggers when “Neighbor becomes offset betterthan serving”. That is, measurement reporting is triggered when channelquality of a neighbor cell is better than that of the serving cell by apreset threshold. However, the A3 measurement event is not suitable forsolving a problem of interference between interfering communicationtechnologies coexisting in the same user equipment. This is because aninterfering communication technology transmitting signals may affect notonly the serving cell but also neighbor cells through interference.

Hence, it is necessary to configure measurement settings inconsideration of an A2 measurement event (“Serving becomes worse thanthreshold”). In other words, it is necessary to trigger measurementreporting when signal quality of the serving cell becomes worse than apreset threshold.

As a precondition for measurement configuration based on an A2measurement event, it is necessary for the user equipment to reportactivation of an interfering communication technology to the eNB. Uponreception of the activation report, the eNB notifies the user equipmentof appropriate measurement objects and a reporting configuration.

Referring to FIG. 4, the UE 401 detects activation of an interferingcommunication technology at step 405. Here, the UE 401 may detectactivation of or an activation request for an interfering communicationmodule. The UE 401 needs to detect activation of an interferingcommunication technology that may potentially interfere with cellularcommunication like LTE operation. To achieve this, the UE 401 may detectactivation of a GPS module, a WiFi module, or a Bluetooth module by theuser, or may detect potential interference while measuring quality of areceived signal from a base station.

The UE 401 checks possibility of interference caused by the interferingcommunication technology, and identifies, when the interferingcommunication technology may cause interference, at least one frequencythat is likely to be affected by the interfering communicationtechnology at step 407. Among frequencies supported by the UE 401(including the serving frequency), a frequency supported by the systemthat is not sufficiently separated from the frequency of the interferingcommunication technology may be regarded as a frequency that is likelyto be affected by interference. For example, a frequency that is likelyto be affected by interference indicates a frequency that may disruptcommunication of a user equipment at present or in the near future ifused by the user equipment.

For step 407, the eNB 403 uses system information blocks (SIB) toprovide information regarding frequencies supported by the system to theUE 401. For example, SIB 5 may include information on frequencies usedby neighbor E-UTRA (LTE) cells or other E-UTRA cells; SIB 6 may includeinformation on frequencies used by neighbor UTRA (3G) cells or otherUTRA cells; SIB 7 may contain information on frequencies used byneighbor GERAN (2G) cells or other GERAN cells; and SIB 8 may includeinformation on frequencies used by neighbor CDMA2000 cells or otherCDMA2000 cells.

A reason for examining those frequencies supported by the system amongthe frequencies supported by the user equipment is that it is possiblefor the user equipment in motion to perform handover to one of thefrequencies supported by the system. Here, sufficiency of separation toavoid coexistence interference depends upon a filtering capability ofthe user equipment.

When at least one frequency that is likely to be affected byinterference is present, the UE 401 sends a measurement configurationrequest message to the eNB 403 at step 409. Here, the measurementconfiguration request message is an RRC message including a list offrequencies that are likely to be affected by interference, and requeststhe eNB 403 to specify measurement objects and reporting configurations.As an example, entries of the list of frequencies that are likely to beaffected by interference may correspond to frequencies to be specifiedas a measurement object.

Upon reception of the RRC message (e.g., the measurement configurationrequest message), the eNB 403 determines necessity of measurementconfiguration for the UE 401 in consideration of the frequencies thatare likely to be affected by interference at step 411. When the servingfrequency of the UE 401 is a frequency that is likely to be affected byinterference, the eNB 403 may configure measurement based on an A2measurement event.

When a measurement configuration is necessary, the eNB 403 sends ameasurement configuration message to the UE 401 at step 413. Here, themeasurement configuration message is an RRC message includinginformation on a measurement configuration. More than one measurementmay be configured. The measurement configuration may include anindication indicating measurement of in-device interference caused by aninterfering communication technology in the UE 401.

The UE 401 performs measurement according to the measurementconfiguration specified by the eNB 403 at step 415.

In WiFi or Bluetooth communication, as uplink transmission is notcontinuous, some (e.g., not all) LTE subframes may be affected byinterference caused by WiFi or Bluetooth transmission. If the UE 401produces a measurement result by averaging measurement values for allsubframes, the eNB 403 may not receive an appropriate measurementresult. In other words, the eNB 403 may receive only a measurementresult obtained by averaging measurement values for all subframes, butsuch a measurement result does not indicate severity and frequency ofinterference.

In an exemplary embodiment, to solve the above problem, if an indicationindicating measurement of in-device interference caused by aninterfering communication technology is received from the eNB 403, thenthe UE 401 maintains two measurement results: one measurement result forsubframes not affected by in-device interference and another measurementresult for subframes affected by in-device interference.

In the event that LTE downlink signal reception is affected by in-deviceinterference caused by an interfering communication technology, the UE401 starts to conduct inter-frequency measurement even though signalquality of the serving cell is greater than an “s-Measure” valuereceived from the eNB 403. The UE 401 determines necessity of reportingbased on an A2 measurement event by comparing the measurement result forsubframes affected by the interfering communication technology with athreshold received from the eNB 403.

When the trigger condition for measurement as to the interferingcommunication technology is met, the UE 401 sends a measurement reportmessage including a measurement report to the eNB 403 at step 417. Here,the measurement report includes a measurement result for subframesaffected by in-device interference and another measurement result forsubframes not affected by in-device interference.

In an exemplary embodiment, the measurement report may include a ratioof subframes affected by in-device interference to subframes notaffected by in-device interference. The measurement report may include ameasurement result for all subframes without classifying subframesaccording to in-device interference. The measurement report may furtherinclude measurement results for available frequencies (e.g.,inter-frequency measurement). Specifically, the measurement report mayinclude measurement results for N cells exhibiting best signal qualitiescorresponding to available frequencies.

Upon reception of the measurement report, the eNB 403 determinesnecessity of handover of the UE 401. If handover of the UE 401 isnecessary, then the eNB 403 determines a target cell to which the UE 401is to be handed over, performs operations necessary for handover, andsends a handover command to the UE 401 at step 419.

FIG. 5 is a flowchart of a procedure performed by an UE 401 such as, forexample, the user equipment provided in FIG. 4 according to an exemplaryembodiment of the present invention.

Referring to FIG. 5, the UE 401 detects activation of an interferingcommunication technology at step 503. Upon detection of activation of aninterfering communication technology, the UE 401 identifies at least onefrequency that is likely to be affected by the interfering communicationtechnology at step 505. If at least one frequency that is likely to beaffected by interference is present, then the UE 401 sends a measurementconfiguration request message to the eNB 403 at step 507. Here, themeasurement configuration request message is an RRC message including alist of frequencies that are likely to be affected by interference, andrequests the eNB 403 to specify measurement objects and measurementconfigurations.

Thereafter, the UE 401 receives a measurement configuration messageincluding information on measurement objects and measurementconfigurations from the eNB 403 at step 509. The UE 401 performsmeasurement according to the measurement configurations specified in themeasurement configuration message at step 511.

When a trigger condition is met during measurement, the UE 401 sends ameasurement report message to the eNB 403 at step 513.

If a handover command message is received from the eNB 403, then the UE401 performs handover according to the handover command message at step515.

The UE 401 starts the interfering communication technology if necessaryat step 517. Thereafter, the UE 401 returns to step 503 and performsrequested operations (such as detection of activation or stoppage ofinterfering communication technologies).

FIG. 6 is a message sequence chart illustrating an interferencemeasurement method according to an exemplary embodiment of the presentinvention.

Referring to FIG. 6, a UE 601 performs a procedure for RRC connectionsetup with an eNB 603 through a network access process at step 605. TheUE 601 detects activation of or an activation request for an interferingcommunication technology that may affect LTE communication or may beaffected by LTE communication through coexistence interference at step607. As previously described in connection with FIG. 4, the UE 601 needsto detect activation of an interfering communication technology that maypotentially interfere with cellular communication like LTE operation. Toachieve this, the UE 601 may sense activation of a GPS module, a WiFimodule, a Bluetooth module, or the like by the user or may detectpotential interference while measuring quality of a received signal froma base station.

The UE 601 communicates with the eNB 603 so as not to use an LTEfrequency band that may potentially interfere with the interferingcommunication technology. To achieve this, the UE 601 selects apreferred frequency that does not interfere with the interferingcommunication technology, and sends an RRC message to the eNB 603 tonotify the same of the preferred frequency at step 609.

In step 609, the UE 601 identifies the operating frequency (or frequencyband) of the interfering communication technology. This frequency (orfrequency band) is referred to as frequency A (or frequency band A).

The UE 601 also identifies the frequency (or frequency band) supportedby the current cellular system (e.g., LTE, UMTS or GSM) amongfrequencies supported by the UE 601. The frequency (or frequency band)supported by the system is referred to as frequency B (or frequency bandB).

The UE 601 may obtain information on frequency B from the cellularsystem, and may receive information on supported frequencies therefrom.More specifically, if a measurement object is configured for the UE 601in the current cell, then the UE 601 may consider the frequencyassociated with the measurement object as frequency B. When SIB 5including an inter-frequency carrier frequency list(InterFreqCarrierFreqList) is received from the cellular system andstored, the UE 601 may consider a frequency included in theinter-frequency carrier frequency list among downlink carrierfrequencies (dl-CarrierFreq) supported by the UE 601 as frequency B.UTRA frequencies belonging to a UTRA-FDD carrier frequency list(carrierFreqListUTRA-FDD) or UTRA-TDD carrier frequency list(carrierFreqListUTRA-TDD) included in SIB 6 may be considered asfrequency B if such frequencies are supported by the UE 601. GSMfrequencies included in SIB 7 may also be considered as frequency B ifsuch frequencies are supported by the UE 601.

The UE 601 selects preferred frequencies among those frequenciesregarded as frequency B (i.e., among frequencies supported by both theUE 601 and the system) in consideration of those frequencies regarded asfrequency A. For example, the UE 601 may select one of the frequenciesregarded as frequency B that is sufficiently separated from frequency Aas a preferred frequency. Alternatively, the UE 601 may select one ofthe frequencies regarded as frequency B that is not sufficientlyseparated from frequency A as a non-preferred frequency. For example,sufficiency of separation to avoid coexistence interference depends upona filtering capability of the UE 601.

Thereafter, the UE 601 creates a preferred frequency list (or anon-preferred frequency list) according to the above described scheme.The UE 601 sends an RRC message including the preferred frequency list(or the non-preferred frequency list) to the eNB 603 at step 609.

Upon reception of the RRC message, the eNB 603 stores the preferredfrequency list (or the non-preferred frequency list) included in the RRCmessage. The eNB 603 checks whether the frequency currently used by theUE 601 is on the preferred frequency list.

If the frequency currently used by the UE 601 is not on the preferredfrequency list, then the eNB 603 instructs the UE 601 to conducthandover to one frequency of the preferred frequency list at step 611.

If the frequency currently used by the UE 601 is on the preferredfrequency list, then the eNB 603 may not instruct the UE 601 to conductimmediate handover. Later, when handover is requested, the eNB 603 mayinstruct the UE 601 to conduct handover to another eNB using a frequencyon the preferred frequency list, which has been stored.

In other words, if the current operating frequency of the UE 601 is nota preferred frequency, the eNB 603 checks possibility of handover of theUE 601 to a preferred frequency and initiates a handover procedure whenhandover of the UE 601 to a preferred frequency is possible.

If handover of the UE 601 to a preferred frequency is not possible (forexample, lack of resources in eNBs using preferred frequencies, orabsence of neighbor eNBs using preferred frequencies), the eNB 603 maysend an RRC message to the UE 601 to notify of impossibility of handoverto a preferred frequency. Upon reception of the RRC message, the UE 601may provide the RRC message to the user, so that the user may decidewhether to start the interfering communication technology if it is notyet started.

After handover to a preferred frequency (or while already using apreferred frequency), the UE 601 starts the interfering communicationtechnology at step 613. Here, two collocated communication technologies(for example, LTE and Bluetooth) may operate simultaneously.

When stoppage or turning off of the interfering communication technologyis detected at step 615, the UE 601 sends an RRC message to the eNB 603to notify stoppage of the interfering communication technology or anupdated preferred frequency list (or non-preferred frequency list) atstep 617. Upon reception of the RRC message, the eNB 603 removesrestrictions on the corresponding frequency and stores the updatedpreferred frequency list (or non-preferred frequency list) for lateruse.

FIG. 7 is a flowchart of a procedure performed by an UE such as, forexample, the UE 601 provided in FIG. 6 according to an exemplaryembodiment of the present invention.

Referring to FIG. 7, the UE 701 detects activation of an interferingcommunication technology at step 703. Upon detection of activation of aninterfering communication technology, the UE 701 identifies at least onefrequency that is likely to be affected by the interfering communicationtechnology at step 705.

If at least one frequency that is likely to be affected by interferenceis present, then the UE 701 sends an RRC message including a list offrequencies that are likely to be affected by interference to the eNB atstep 707.

The eNB may send a handover command. When a handover command message isreceived from the eNB, the UE 701 performs handover according to thehandover command message at step 709.

The UE 701 starts the interfering communication technology if necessaryat step 711. Thereafter, the UE 701 returns to step 703 and performsrequested operations (such as detection of activation or stoppage ofinterfering communication technologies).

FIG. 8 is a block diagram of a user equipment according to an exemplaryembodiment of the present invention.

Referring to FIG. 8, the user equipment may include a transceiver unit801, a mux/demux unit 803, an upper layer unit 805, a control messagehandler 807, a control unit 809, an interfering technologydetector/determiner 811, and an interfering communication module 813.

In the user equipment, data is sent and received through the upper layerunit 805, and control messages are sent and received through the controlmessage handler 807. For transmission, data is multiplexed by themux/demux unit 803 and sent through the transceiver unit 801 undercontrol of the control unit 809. For reception, a message signalreceived by the transceiver unit 801 is demultiplexed by the mux/demuxunit 803 and forwarded to the upper layer unit 805 or the controlmessage handler 807 according to the message type, under control of thecontrol unit 809.

As an example, the interfering communication module 813 may directlysend notification of a power on or start of operation to the interferingtechnology detector/determiner 811. The interfering technologydetector/determiner 811 may already be aware of the interferingcommunication module 813. When a transmit signal 815 sent by theinterfering communication module 813 is received by the transceiver unit801 as a strong interference signal 817, the control unit 809 mayrecognize this situation and notify the interfering technologydetector/determiner 811 of in-device interference.

To avoid in-device interference, the interfering technologydetector/determiner 811 notifies the control message handler 807 ofinformation on the interfering communication module 813. Then, thecontrol message handler 807 creates an RRC message including ameasurement configuration request and a preferred frequency list (or anon-preferred frequency list, and sends the RRC message to acorresponding eNB.

When a measurement configuration message is received as a controlmessage from the eNB, the control unit 809 controls an operation toperform measurement according to the measurement configuration. When ahandover command message is received as a control message from the eNB,the control unit 809 controls an operation to perform handover accordingto the handover command. After successfully performing handover, thecontrol unit 809 notifies the interfering technology detector/determiner811 of handover completion so as to start the interfering communicationmodule 813 if not yet started. Thereafter, the control unit 809 controlsan operation to detect activation or stoppage of interferingcommunication technologies, and the user equipment may repeat the aboveprocess.

Although the user equipment is depicted as including multiple blockshaving different functions in the above description, it is notnecessarily limited to such a configuration.

For example, the user equipment may be composed of a transceiver unit tosend and receive a signal to and from an eNB, and a control unit tocontrol interference measurement.

In this case, the control unit may control a process of identifying,upon detection of activation of an interfering communication technology,those frequencies that are likely to be affected by interference causedby the interfering communication technology, sending a measurementconfiguration request message including a list of frequencies that arelikely to be affected by interference to a corresponding eNB, andperforming, upon reception of a measurement configuration message fromthe eNB, measurement according to measurement configurations specifiedin the received message.

For example, the measurement configuration message may include anindication indicating measurement of in-device interference caused by aninterfering communication technology in the user equipment.

The control unit may control an operation to separately store ameasurement result for subframes not affected by in-device interferenceand another measurement result for subframes affected by in-deviceinterference. The control unit may regard a frequency that is supportedby the user equipment and is not separated by a preset gap or more fromthe frequency of the interfering communication technology as a frequencythat is likely to be affected by interference.

When a trigger condition in the measurement configuration message ismet, the control unit may control an operation to send a measurementreport message including measurement results to the eNB. Here, themeasurement report message may separately include a measurement resultfor subframes not affected by in-device interference and anothermeasurement result for subframes affected by in-device interference.

When a handover command based on the transmitted measurement results isreceived from the eNB, the control unit may control an operation toperform handover according to the handover command.

As described above, a user equipment supporting the proposed method mayperform effective measurement as to a present or potential interferencefactor, report measurement results to a corresponding base station, andperform handover to another cell so as to reduce in-device interference.Hence, the user equipment may conduct smooth communication whileavoiding coexistence interference caused by an interfering communicationtechnology.

In a feature of various exemplary embodiments of the present invention,a user equipment supporting the proposed method may provide informationregarding a frequency band that can be affected by interference to acorresponding base station, which is then recommended to send a commandfor guiding interference avoidance to the user equipment. Hence, it ispossible for the user equipment to perform smooth communication byreducing interference between communication modules.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

1. A measurement method for a user equipment in a wireless communicationsystem, the measurement method comprising: identifying, upon detectionof activation of an interfering communication technology thatpotentially causes interference to cellular communication of the userequipment, at least one frequency that is likely to be affected by thepotential interference; sending a measurement configuration requestmessage including the identified frequency that is likely to be affectedby the potential interference to a base station; and performing, uponreception of a measurement configuration message from the base station,measurement according to measurement configurations included in themeasurement configuration message.
 2. The measurement method of claim 1,wherein the received measurement configuration message includes anindication indicating measurement of in-device interference caused bythe interfering communication technology in the user equipment.
 3. Themeasurement method of claim 2, wherein the performing of the measurementaccording to the measurement configurations comprises separately storinga measurement result for subframes not affected by in-deviceinterference and another measurement result for subframes affected byin-device interference.
 4. The measurement method of claim 1, whereinthe identifying of at least one frequency that is likely to be affectedby the potential interference comprises determining a frequency that issupported by the user equipment and that is not separated by a presetgap or more from the frequency of the interfering communicationtechnology as a frequency that is likely to be affected by the potentialinterference.
 5. The measurement method of claim 1, further comprisingcreating, when a trigger condition specified in the measurementconfiguration message is met, a measurement report message includingmeasurement results, and sending the measurement report message to thebase station.
 6. The measurement method of claim 5, wherein themeasurement report message separately includes a measurement result forsubframes not affected by in-device interference and another measurementresult for subframes affected by in-device interference.
 7. Themeasurement method of claim 6, further comprising: receiving a handovercommand reflecting the measurement results from the base station; andperforming handover according to the received handover command.
 8. Auser equipment capable of interference measurement in a wirelesscommunication system, the user equipment comprising: a transceiver unitfor sending and receiving a signal to and from a base station; and acontrol unit for controlling a process of identifying, upon detection ofactivation of an interfering communication technology that potentiallycauses interference to cellular communication of the user equipment, atleast one frequency that is likely to be affected by the potentialinterference caused by the interfering communication technology, forsending a measurement configuration request message including theidentified list of at least one frequency that is likely to be affectedby the potential interference to the base station, and for performing,upon reception of a measurement configuration message from the basestation, measurement according to measurement configurations specifiedin the received message.
 9. The user equipment of claim 8, wherein thecontrol unit receives, through the transceiver unit, a measurementconfiguration message including an indication indicating measurement ofin-device interference caused by the interfering communicationtechnology in the user equipment.
 10. The user equipment of claim 9,wherein the control unit controls an operation to separately store ameasurement result for subframes not affected by in-device interferenceand another measurement result for subframes affected by in-deviceinterference.
 11. The user equipment of claim 8, wherein the controlunit determines a frequency that is supported by the user equipment andis not separated by a preset gap or more from the frequency of theinterfering communication technology as a frequency that is likely to beaffected by the potential interference.
 12. The user equipment of claim8, wherein the control unit controls, when a trigger condition specifiedin the measurement configuration message is met, an operation to createa measurement report message including measurement results, and to sendthe measurement report message to the base station.
 13. The userequipment of claim 12, wherein the control unit sends, through thetransceiver unit, a measurement report message separately including ameasurement result for subframes not affected by in-device interferencecaused by the interfering communication technology and anothermeasurement result for subframes affected by in-device interference. 14.The user equipment of claim 13, wherein the control unit controls, uponreception of a handover command reflecting the measurement results fromthe base station, an operation to perform handover according to thereceived handover command.
 15. A system for coordinating measurement ofin-device interference, the system comprising: a base station; and aterminal that communicates with the base station, wherein the basestation instructs the terminal to measure in-device interference if theterminal determines that an interfering communication technology isactivated as the terminal is communicating with the base station. 16.The system of claim 15, wherein upon detection of the activation of theinterfering communication technology, the terminal identifies at leastone frequency that is likely to be affected by potential interferencefrom the interfering communication technology.
 17. The system of claim16, wherein the terminal identifies at least one frequency that islikely to be affected by potential interference from the interferingcommunication technology by determining frequencies over which theterminal communicates that are within a predefined threshold from thefrequency over which the interfering communication technology is capableof communicating.
 18. The system of claim 15, wherein the base stationcoordinates a handover with the terminal to a frequency which willlikely not suffer interference from the interfering communicationtechnology.
 19. The system of claim 15, wherein the terminal, uponreceipt of instructions from the base station to measure in-deviceinterference, transmits a message which separately indicates ameasurement result for subframes not affected by in-device interferenceand a measurement result for subframes affected by in-deviceinterference.